* {
  mark: symbol(circle);
}

:mark {
  fill: #CC3300;
}

[ @scale < 16000000] {
  mark-size: 12;
}

[ @scale > 16000000] [ @scale < 32000000] {
  mark-size: 8;
}

[ @scale > 32000000] {
  mark-size: 4;
}